Design of hybrid bridge girders with adhesively bonded and compositely acting FRP deck

Analytical prediction methods for axial stresses and deflections at the serviceability limit state and for ultimate failure loads are proposed for hybrid bridge girders consisting of FRP bridge decks adhesively bonded to steel girders. The methods allow for the consideration of partial shear connection layers in hybrid cross-sections. It was found that the adhesive bond always provides full composite action between FRP decks and steel girders, even in the case of flexible polyurethane adhesives with a layer thickness up to 50 mm. For pultruded bridge deck systems, however, the webs or diagonals between the upper and lower face panels provide only partial shear connection of the upper face panels in the longitudinal bridge direction. The results of these prediction methods were compared to experimental results from full-scale girders with two different pultruded FRP bridge deck systems and were found to match well.